make it possible to disable internal tracing in unofficial builds

base/debug/trace_event.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // This header file defines the set of trace_event macros without specifying
 // how the events actually get collected and stored. If you need to expose trace
 // events to some other universe, you can copy-and-paste this file as well as
 // trace_event.h, modifying the macros contained there as necessary for the
 // target platform. The end result is that multiple libraries can funnel events
 // through to a shared trace event collector.
@@ skipping 210 matching lines @@
 //   literals). They may not include " chars.
 #define TRACE_EVENT0(category_group, name) \
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name)
 #define TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val)
 #define TRACE_EVENT2(category_group, name, arg1_name, arg1_val, arg2_name, \
                      arg2_val) \
     INTERNAL_TRACE_EVENT_ADD_SCOPED(category_group, name, arg1_name, arg1_val, \
         arg2_name, arg2_val)
 
-// Same as TRACE_EVENT except that they are not included in official builds.
-#ifdef OFFICIAL_BUILD
+// UNSHIPPED_TRACE_EVENT* are like TRACE_EVENT* except that they are not
+// included in official builds.
+
+#if OFFICIAL_BUILD
+#undef TRACING_IS_OFFICIAL_BUILD
+#define TRACING_IS_OFFICIAL_BUILD 1
+#elif !defined(TRACING_IS_OFFICIAL_BUILD)
+#define TRACING_IS_OFFICIAL_BUILD 0
+#endif
+
+#if TRACING_IS_OFFICIAL_BUILD
 #define UNSHIPPED_TRACE_EVENT0(category_group, name) (void)0
 #define UNSHIPPED_TRACE_EVENT1(category_group, name, arg1_name, arg1_val) \
     (void)0
 #define UNSHIPPED_TRACE_EVENT2(category_group, name, arg1_name, arg1_val, \
                                arg2_name, arg2_val) (void)0
 #define UNSHIPPED_TRACE_EVENT_INSTANT0(category_group, name, scope) (void)0
 #define UNSHIPPED_TRACE_EVENT_INSTANT1(category_group, name, scope, \
                                        arg1_name, arg1_val) (void)0
 #define UNSHIPPED_TRACE_EVENT_INSTANT2(category_group, name, scope, \
                                        arg1_name, arg1_val, \
@@ skipping 1288 matching lines @@
   const char* name_;
   IDType id_;
 
   DISALLOW_COPY_AND_ASSIGN(TraceScopedTrackableObject);
 };
 
 } // namespace debug
 } // namespace base
 
 #endif /* BASE_DEBUG_TRACE_EVENT_H_ */